The catalytic hydrodesulfurization and hydrofining of hydrocarbon fractions is well known at this stage of the refining art. A great variety of catalysts and processing inovations have also been proposed for use. The primary requisites of the prior art catalysts are that they exhibit a high degree of activity for the hydrogenation reaction to be accomplished so that decomposition of the sulfur compounds in the charge as well as decomposition of nitrogen and/or oxygen compounds will be accomplished. It is also desirable in many of these hydrogenation reactions to minimize the scisson of carbon to carbon bonds resulting in the production of undesired light gases. It is also desirable in some hydrogenation processes to summarize the hydrogenation of some desired constituents comprising the feed being processed. It is known that most of the transitional metal oxides and sulfides which are not poisoned by sulfur, possess desired hydrodesulfurization activity. Some of the best known catalysts suitable for this purpose are cobalt molybdate supported on alumina, nickel-tungsten sulfide on various supports such as alumina and silica-alumina, molybdenum on alumina as well as some vanadium-alumina catalysts alone or promoted with magnesia.
Hydrogenation processes are subject to effecting olefin saturation which not only consumes hydrogen but lowers the octane number of resulting product such as gasoline product. At the present time it is desirable to reduce process economies and in the case of gasoline production it is desirable to maintain process derived gasoline product octane values in conjunction with providing an acceptable sulfur level in the product. This has become increasingly important with the environmental demands for high octane unleaded gasolines satisfying the requirements of the day and near future.